As paintball technology has developed
over the years, one design focus for both paintguns and aftermarket accessories
has been to properly feed paintballs without breaking them. Especially
with the rough bolt force found in blowback semi-autos, if the bolt closes
when a paintball is only partially fed, chances are pretty good that ball
will be chopped in half, leaving a gooey mess in the paintgun, and filling
the barrel with paint that will cause spin and hook-shots. A few
years back the folks at JAM Enterprises came up with a simple solution
– the JAM Bolt.

Basically
the Jam bolt is a two piece bolt, with a spring-loaded telescoping design.
The paintgun links to one portion of the bolt, and moves that as the paintgun’s
stock bolt would.

The second piece of the bolt is connected
to the first by a spring. In a normal loading situation, both pieces
of the bolt move back and forth together, chambering a paintball.
In the case of a mis-feed however, the front part of the bolt stops on
the obstruction, and the spring compresses while the back portion continues
to move forward. The design is a very simple approach to a common
problem in that rather than re-designing the paintgun, or adding a ball
sensor and electronics, it is built to prevent chops by simply being a
gentler bolt.

Additionally,
in most of the JAM Bolt designs, the bolt’s gas port is located in the
front bolt half. If the bolt doesn’t close, the gas port doesn’t
line up with that of the paintgun, preventing a full blast of gas from
blowing through the bolt face, also reducing the chance of a break, and
the chance of any debris from a break being blown up the feed port into
the hopper where it can cause more problems.

Since the initial release of the JAM
Bolt as an aluminum bolt, JAM Enterprises has moved on to a combination
of aluminum and acetal resins (like Delrin – a registered trademark of
the DuPont Corp., who’s attorneys send us nasty-grams if we don’t mention
them.) This produces a low friction, light weight “self lubricating”
bolt, but also gives additional strength where it is needed. While
the early JAM bolts were for the Autococker, the company has since produced
models for many paintguns including Spyders, Intimidators, and Angels.

For review we looked at three JAM Bolts,
and put two of them in the field. The Spyder Rear Cocking JAM Bolt
has a long rear half, which serves as the cocking knob, and is compatible
with a number of rear cocking Spyder Models. It is interesting to
note that while the JAM Bolts have been available for a few years now,
they have not received as much attention as the very similar anti-jam bolts
Kingman is now putting in Spyders, likely due to the power of Kingman’s
marketing and advertising compared to that of a smaller company.

For the Intimidator and Autococker,
the JAM Bolts were a simple drop-in upgrade, though a little extra effort
was needed for a proper fit on a CCM J2.

For
the Autococker style JAM Bolts, the bolt link pin locks into an aluminum
back piece that rides inside the acetal resin bolt body. The body
itself has to slide freely in the gun’s cocking block for the anti-chop
feature to work properly. A black o-ring acts as a bumper to minimize
wear on the back of the bolt where it impacts with the cocking block.
On the J2 cocking bolt, that o-ring caused sufficient friction that the
bolt could not slide smoothly. Lubricating the o-ring with paintgun
oil and working it back and forth a while achieved the proper low-friction
fit necessary.

On the field, the bolts worked well,
and chopping was not a problem. To try and force a chopping problem,
an Apache loader was used on the J2, and simply turned off, so that it
would be likely to not keep up under rapid fire. Numerous misfires
occurred, but only one resulted in a broken ball with Hellfire paint.
Running the bolt without the o-ring to provide minimal friction against
the cocking block resulted in no breaks during intentional misfires.

With the many options available to combat
chopping or paint, the JAM Bolt proved to be a very simple drop in solution.

The author would like
to thank Clint Marshall for field testing the Intimidator model.